The present invention relates to a method for controlling the volume level of sound which can reduce the tint phenomenon of a screen by controlling the center level of OSD on-screen display using 0-64 levels for the OSD according to the output of a MICOM(Microcomputer), in the display apparatus of various electric systems with the OSD faculty using the level controlled by a PWM(Pulse Width Modulation) manner.
Generally, in the electric systems such as TV, VCR and audio in a MICOM which can control the pulse width and the OSD faculty is possible. When the volume of sound is controlled by using the PWM output and the OSD faculty, a 6-bit PWM output signal can control 64 levels and the controlled level is displayed by a bar type through the OSD, where the bar appears every two levels, that is, totally 32 bars. But, in this case, the lowest level is 0-level, while the highest level is 63-level, so that the OSD is displayed by 63 levels even if 64 levels is possible for the OSD. Thus, under the PWM output with 63 levels, the center bar is not determined, so that the tint of the screen can not be controlled accurately. That is, the brightness becomes a maximum at the center bar, while the center bar is placed between 16th and 17th bars under 63 levels, so the accurate adjustment of brightness is impossible.